reference to book or site requested

Dear gnustep,

I hope that you will accept a most trivial question. I would like a 
solution to my problem, but more so referral to a book or other source 
of information.

I am a reasonably skilled amateur Mac programmer with too little UNIX 
understanding to do what I have embarked on. I am currently getting my 
feet wet on X-11 for the purpose of doing some bioinformatics where a 
lot of code is out there, made for Linux usually. My mac programming 
skills help me little and I stumble over trivial things. I can download 
nedit and get it to launch X-11 by double-clicking nedit. If I type 
'nedit' into Xterm, however,  I get the message that it is an unknown 
command unless I move to were it is and then type ./nedit. While this 
works, I cannot add it to the list of X-11 apps because the command 
does not work.
Either I have to put the nedit executable somewhere special or tell the 
system that a new command has been installed.

Most UNIX books that I have come across are either too simple and 
assumes that you never need to install or compile anything, or they are 
written for knowledgeable UNIX programmers who don't have problems of 
this  sort but need to know what a Mac is. Where is the book (or 
web-site) for the Mac savvy programmer who is an absolute beginner when 
it comes to UNIX development?

Thanks for your time,

Peter Ulvskov